The specific aims of Phase I are to develop software programs to implement two methods of hearing threshold estimation that simultaneous acquisition of two audiograms, one from each ear, and to develop VRA- based behavioral training and testing techniques that allow infants to respond with accuracy and reliability to sounds presented via insert earphones. Two new algorithms will be developed, CAST-2 and OHTA-2, based on their namesakes, CAST (Classification of Audiograms by Sequential Testing) and OHTA (Optimized Hearing Test Algorithm) which were developed originally for sound-field testing. During Phase I, the independent ear-test versions will be written, tested with computer simulation and piloted with human infants. The new algorithms will be compared in terms of 1) threshold agreement with independent left and right ear tests and 2) time for testing two ears with time for independent tests. In Phase II, each of the algorithms will be tested on a large and varied population of children including: 1) high-risk infants who were screened with ABR and/or OAE in a newborn nursery, 2) normal children in a pediatric practice, and 3) children referred to an otolaryngology department of a large city hospital. Independent ear audiograms obtained with IVRA will be compared to other measures of infant hearing (e.g., ABR, immittance, OAE).